Pumping system



C. KROLL PUMPING SYSTEM Dec. 26, 1950 Filed July 26, 1946 Patented Dec.26, 1950 UNITED STATES PATENT OFFICE PUMPING SYSTEM Cornelius Kroll,Houston, Tex.

Application July 26, 1946, Serial No. 686,362

9 Claims.

This invention relates to pumping systems.

In certain pumping systems, for example in systems used for pumpinggasoline from tank barges, it is desirable to use a pump installed onthe deck of the tank barge for safety and elimination of fire hazard andto use a centrifugal pump because of its relatively large capacity.However,

such pump creates a negligible suction lift until the pump itself iscompletely filled with liquid. In such a system, therefore, it isnecessary to prime the pump and maintain the prime so that it willproperly function. In pumping volatile liquid, vapor locks sometimesoccur in the system, causing the pump to lose its prime. When the levelof the liquid being pumped nears the bottom of the tank, a certainamount of air is entrained with the liquid which. also causes a pump tolose its prime.

An important object of the present invention is to provide a novelpumping system wherein means is employed for establishing the initialpriming and maintaining such priming of the liquid pump whereby suchpriming is effected without the necessity for having to resort to manualpriming.

A further object is to provide such a system wherein the use of acentrifugal liquid pump is rendered practicable by the use of anauxiliary priming system including a vacuum pump which effects theinitial and continuing flooded suction necessary for its normaloperation.

Other objects and advantages of the invention will become apparentduring the course of the following description.

In the drawing I have shown one. embodiment of the invention. In thisshowing:

The figure is a sectional-diagrammatic representation of the system,parts being shown in elevation and parts being broken away.

Referring to the drawing, the numeral I designates a conventional pump,preferably of the centrifugal type because of its relatively largecapacity. The use of this type of pump is particularly subject todifficulty under certain conditions and this difficulty is overcome withthe-.-

present system, rendering it fully practicable to employ a centrifugalpump. The pump I0 is provided with an, inlet duct ll one end of whichextends downwardly into the liquid to be pumped and may be provided atits lower end with a bell y mouth ll. Liquid flows through duct II inthe direction of the arrow into the pump to be pumped therefrom throughan outlet pipe [2 provided with a check valve l2, to any suitable point.The pump I0 is driven by an engine or mew-113) other power source [3,and this source also drives a vacuum pump I lfor a purpose to bedescribed.

A tank IB is divided transversely by a vertical wall iii to formchambers 20 and 2|. The chamber 20 is adapted to contain a body of a.liquid which may be at the level indicated by the line 22, this levelbeing maintained in a manner to be described.

A duct 25 has its one end tapped intothe intake. duct II and has its.other end opening into the chamber 20 and is provided with a check;valve 26 opening outwardly relative to the chamber 20. The check valve26 functions to permit the flow of liquid from the chamber 2|] into theinlet duct ll under certain conditions to be described, but prevents anyflow of liquid into the chamber 20, at this point. i

A second pipe 21 is tapped into the duct I l and has its other endcommunicating with the chamber 25 above the liquid level 22 therein.Within the length of the pipe 21 is arranged a valve casing, 28 having aseat 29 engaged by a valve. 30 connected to a diaphragm 3| and urged toclosed position by a spring 32. This spring may be arranged within acasing 33. Casing 33 is connected by a pipe 34 to the pipe 21 above thevalve 30, thereby subjecting the interior of the casing 33 to thepressure of the chamber 2|) for a purpose to be described.

The wall I9 is provided near the top of the chambers 20 and 2! with aduct 35 in open communication with the chamber 2|. The other end of thisduct is closed, and the top and bottom of the duct are provided withvalve seats 36 and 3.1 respectively engageable by valves 38 and 39.These valves are carried by a depending stem 43 to the lower end ofwhich is connected a float M. This float rises and falls with the levelof the liquid in the chamber 20 and assists in determining the level ofsuch liquid as will become apparent.

A duct 45. opens into chamber 20. This duct is connected at itsother endto the intake side of the vacuum pump [4 whereby the latter exhaustsgaseous fluids from the chamber 20. The outlet of the pump I4 isconnected by a duct 46. to the upper part of the chamber 2|. The arrowsassociated. with the ducts 45 and 46. indicate the direction of flow ofgaseous fluids through these ducts. Chamber 2| is open to theatmosphere, preferably through a. vertically extending, vent A duct hasone end opening into the chamber 20 and has its other end, within thechamber 1 2! closed, as shown. The duct 55 is provided with upper andlower ports 56 and 5'! forming valve seats respectively engageable byvalves 58 and 59. These valves are carried by an upwardly extending stemor rod 60 to the upper end of which is connected a float 6| to preventthe accumulation of liquid in the chamber above approximately the levelindicated by the numeral 62.

The operation of the apparatus is as follows:

It will be understood that the representation of the invention in thedrawing is largely diagrammatic and the pump l0 and associated elementsare not necessarily below the tank l8. As a matter of fact, in mostinstallations, the two parts of the apparatus referred to will bearranged side by side, for example on the deck of a tank barge, and theinvention will be particularly described as to its operation on theassumption that the parts are so arranged. Under such conditions, for areason which will become apparent, the liquid level 22 will be arrangedfrom to 36 inches above the inlet of pump l0.

Assuming that the apparatus has been set up on the deck of a tank bargeas described and operation is about to start, the valves 38 and 39, and58 and 59 will be in closed position, there being no liquid in either ofthe chambers 2B and 2|. The check valve 26 will occupy its normal closedposition. Inasmuch as atmospheric pressure will be present in thechamber 28, the spring 32 will hold the valve 30 on its seat. Thisspring is relatively light and accordingly the valve 33 closes at orslightly below atmospheric pressure.

The motor I3 is now started in operation to drive the pump It and thevacuum pump M. A negligible dropping of the pressure in the inlet IIwill occur through the operation of the pump ll] since no liquid will bepresent therein.

However, the vacuum pump l4 constantly ex hausts air from the chamber 20and exhausts it into the chamber 2| at atmospheric pressure for releasethrough the stack 47. All of the valves shown in the drawing will beclosed, as previously stated, and the operation of the vacuum pump l4reduces the pressure in the chamber 2! to I create a partial vacuumtherein. This partial vacuum holds the valve 26 on its seat, but createsdifferential pressures on opposite sides of the diaphragm 3! to move thelatter against the tension of the spring 32 to open the valve Bil.

The partial vacuum in the chamber 28 will be communicated to the pipe21, thence through the inlet duct H to the lower end of such duct belowthe level of the liquid to be pumped.

Atmospheric pressure acting on the surface of such liquid will thenforce it upwardly into the duct H to pump it, and through pipe 2! intothe chamber 263. As soon as the quantity of the liquid is suflicient toflood the suction of the pump Ill it will be fully primed. The normaloperation of this pump will thus be initiated and liquid will be pumpedin the usual way.

The valves 38 and 39 being closed, no air will be admitted through theduct 35 into the chamber 20. The level of the liquid in this chamberaccordingly will rise until the float 4| lifts the valves 38 and 39 fromtheir respective seats 36 and 31. This operation admits air or gaseousfluid at atmospheric pressure into the chamber 20 to limit the decreaseof pressure therein until a pressure balance is reached at which theliquid level will be maintain d at the point 22. Any

tendency for the liquid level to rise will result in opening the valves38 and 39 to a slightly greater extent thus further limiting thedecrease of pressure in the chamber 2t. Any tendency of the liquid level22 to drop will result in closing the valves 38 and 3% completely or toa greater extent, thus decreasing the pressure in chamber 29 on accountof the increased rate of exhaustion of air or gaseous fluid from chamber26 through pipe relative to the admission of air through duct 35. Thiswill result in lowering the pressure in the chamber 23 to maintain thelevel 22.

The partial vacuum necessary in the chamber 28 for maintaining theliquid level 22 will depend upon the difierence in the level 22 and thelevel of the liquid in the barge tank. For example. the pressure headexisting between these two liquid levels at the starting of the pumpingoperation will be less than will be present as pumping progresses. andsuch progressively increasing pressure head requires a progressivelowering of the pressure in the chamber 2%. This is automaticallycompensated for by the operation of the valves 33 and 39 by the Seat M.0bviously, as the pressure head referred to increases, there will be atendency for the liquid level 22 to drop, and this will be accompaniedby a lowering of the valves 38 and to points closer to the closedpositions of the valves. This reduces the rate of admission air orgaseous fluid at atmospheric pressure to the chamber 20 in proportion tothe exhaustion of air through pipe 45, thus automatically maintainingthe proper sub-atmospheric pressure to hold the liquid level 22. 7

Assuming that the apparatus is used for the pumping of volatile liquids,it will be obvious that some gaseous fluids and some entrained liquidwill pass through the pipe 45. vacuum pump l4 and pipe 455 into thechamber 2|. Such vapors will condense and entrained liquid willaccumulate in the chamber 2!, which is always at atmospheric pressure,and the condensation and entrainment will collect in the chamber 2!.Upon the accumulation of sufficient liquid in chamber 2i, the float 6!will raise the valves 53 and 59 to permit the liquid to flow through theduct 55 into the chamber 2%. This flow is effected quite readily in viewof the fact that pres sure in the chamber 2!, during normal operation ofthe apparatus, is always greater than pressure in the chamber to.

From the foregoing it will be apparent that the present system is highlyadvantageous for initiating the op ration of a centrifugal pump forpumping liquid wherein the pump is arranged above the highest level ofthe liquid to be pumped.

However, the system is not limited to such use, as further describedbelow.

it will be recalled that the maintenance of a partial vacu m in thechamber 2i? normally maintains diiferential pressures on opposite sidesof the diaphragm 3.! to hold the valve as in a normal open position.Assuming that a vapor lock occurs in the inlet duct H, the vapor willmove to and thence upwardly through the duct 21 into the chamber 25. Thedevice thus acts to remove such vapors from the line H. The constantlyoperating vacuum pump 14 continuously removes such vapors to maintainsuch partial vacuum in charmber 23 as will maintain a constant liquidlevel 22, thus maintaining a continuously flooded suction of pump i Thusthe system operates to tend to maintain the p mp continuously byremoving from the intake line H the vapors which tend to cause the pumpto lose its prime. The check valve 25 obviously opens to permit the flowof liquid from 5. chamber 20 tending to collect therein in an exmassiveamount either from discharges of chamber H or from the normal surges andentraimnent in chamber 26 incident to the pressure balancing operationof float i and valves 38' and 33. In other words, upon an excessiveaccumulation of liquid in the chamber 29, or upon a drop in pressuretherein incident to the flow of gas thereinto, the head of liquid in thechamber 28 causes the check valve 26 to open and permit the flow ofliquid through pipe 25 into the inlet pipe H. Moreover, the check valve25 prevents the now of liquid. from the inlet duct l i: into the chamber23, thereby forcing all liquid that enters the chamber 28 to flowthrough duct 21 and the control valve 29 in such duct.

The control valve 36) closes approximately at atmospheric pressure whilethe check valve 26 remains normally closed. This arrangement not onlypermits the system to be used under the conditions described above, thatis, with the mechanism arranged wholly above the highest level of theliquid to be pumped, but also permitsthe use of the apparatus where theoperation is started with the level of the liquid to be pumped above theintake of the pump Ill. Such a condition exists, for example, when thepump is installed in a tanker. In such a ship, the pump is set below thedeck and as close to the bottom of the ship as possible. When the pumpis started, therefore, its intake isflooded and accordingly no primingis necessary.

Under the conditions referred to the priming vacuum otherwise maintainedin the chamber 2!) is neutr lized by the maintenance of the valves 38and in open position by the float iI the initial operation of theapparatus resulting in creating a partial vacuum in the chamber 28 toopen the valve at for a sufficient length of time for liquid to flowthrough the pipe 21 into the chamber 2e until the liquid level 22reaches the point where the float ll will maintain the valves 35! and 39in partially open position. When these valves reach a sufficiently openposition approximately atmospheric pressure will be present in thechamber 25] and the spring 32 will close the valve it. No further liquidcan then flow into the charm her 2%. the valve 3 being closed and thevalve 28 obviously preventing any flow of liquid through the pipe 25.

' However, when the level of the liquid in the tank is pumped down tothe point where it drops below the intake of the pump ill, the presentsystem comes into operation to maintain a flooded pump intake. When theliquid level in the tank is pumped down to a point below the level ofthe intake of pump It reducing the pres ure at the intake of pump IE tobelow atmospheric pressure, some of t e li uid in the tank 2!: will flowdownwardly through pipe 25 into the duct I 1 until the valves'38 and 39partially or completely close. Air or ga eous fluid being continuouslyevacuated from chamber 2i! by vacuum pump it will then cause thepressure in chamber 2:! to decrease below atmo pheric pressure openingthe valve 36 and creating the nece sary vacuum in the pipe I I to liftthe liquid to the pump I3 and maintain the priming thereof, all ashereinbefore described.

' The use of double valves 33 and 39 and 58 and 59 is es ential for thepurpose of balancing the forces to which the valve stems are sub ectedto render the valves readily operable by their associated floats. Forexample, the sub-atmospheric pressure normally present in the chamber 28will cause athrust on the face of valve 38 in the opposite direction tothat on the face of the. valve 39; and accordingly the sub-atmosphericpressure will be balanced as to these valves, since they are attached tothe same stem. The same situation exists as to the valves 58 and 59, andthe two sets of double valves. accordingly are completely sensitive tooperation of the associated floats.

The system is particularly highly effective for the pumping of volatileand non-volatile liquids from barges and tankers, and it has been foundthat its operation greatly reduces the time required for such a pumpingoperation. This system is also efiective in what is known as strippingthe tanks by which is meant the practically complete pumping outthereof. By placing the bottom intake of pipe i I with a suitablebellmouth very close to the bottom of the tank, the tanks can becompletely stripped, since the air or gaseous fluid entrained with theliquid when the last. part of the liquid is being sucked up into thepipe 4 I does not cause the pump as to lose its prime. Such entrainedair or gaseous fluids are continuously removed from the suction intakeof pump ill by this system as rapidly as such air or gaseous fluids areentrained or accumulated.

I claim:

l. in a liquid pumping system comprising a. pump having an outlet ductand an inlet duct adapted for connection with a source of liquid topumped, a chamber, a branch duct connecting said chamber to the inletduct of the pump, means operative wholly independently of the pumping orsaid pump for maintaining a level of liquid from said source in saidchamber above the inlet duct of the pump, and means operative upon apredetermined increase in the pressure in said chamber for closing saidbranch duct.

2. In a liquid pumping system comprising a pump having an outlet ductand an inlet duct adapted for connection with a source of liquid to bepumped, a chamber, a branch duct connecting said chamber to the inletduct of the pump, a vacuum pump connected to said chamber for causing areduction in pressure in the inlet duct of the pump and for causing aflow of liquid into said chamber. means for controlling the quantity ofliquid in said chamber to maintain the level thereof at a point abovethe inlet duct of said first named pump. and means operative upon apredetermined increase in the pressure in said chamber for closing saidbranch duct.

3. In a liquid pumping system comprising a pump having an outlet ductand an inlet duct adapted for connection with a source of liquid to bepumped. a chamber, a branch duct connecting said chamber to the inletduct of the pump, a vacuum pump connected to said chamber for causing areduction in pressure in the inlet duct of the pump and for causing aflow of liquid into said chamber, float controlled means in said chamberfor governing the admission of air thereinto to maintain in said chamberthe necessary sub-atmospheric pressure to maintain said level of theliquid therein, and means operative upon a predetermined increase in thepressure in said chamber for closing said branch duct. 7

4. In a liquid pumping system comprising a pump having an outlet ductand an inlet duct adapted for connection with a source of liquid to bepumped, a chamber, a branch duct connecting said chamber to the inletduct of the pump, means operative wholly independently of the pumpingefiect of said pump for maintaining a level of liquid from said sourcein said chamber above the inlet duct of the pump, a valve forcontrolling communication through said branch duct, means biasing saidvalve to closed position, and differential fluid pressure operated meanscomprising a pressure responsive element connected to said valve andhaving one face subject to sub-atmospheric pressure in said chamber tomaintain said valve open when the pressure in said chamber decreases toa predetermined point.

5. In a liquid pumping system comprising a pump having an outlet ductand an inlet duct adapted for connection with a source of liquid to bepumped, a chamber, a branch duct connecting said chamber to the inletduct of the pump, a vacuum pump connected to said chamber for causing areduction in pressure in the inlet duct of the pump and for causing aflow of liquid into said chamber, means for controlling the quantity ofliquid in said chamber to maintain the level thereof at a point abovethe inlet duct of said first named pump, a valve for controllingcommunication through said branch duct, means biasing said valve toclosed position, and diiferential fluid pressure operated meanscomprising a pressure responsive element connected to said valve andhaving one face subject to sub-atmospheric pressure in said chamber tomaintain said valve open when the pressure in said chamber decreases toa predetermined point.

6. In a liquid pumping system comprising a pump having an outlet ductand an inlet duct adapted for connection with a source of liquid to bepumped, a chamber, a branch duct connecting said chamber to the inletduct of the pump, a vacuum pump connected to said chamber for causing areduction in pressure in the inlet duct of the pump and for causing aflow of liquid into said chamber, float controlled means centrifugalpump having an outlet duct and an inlet duct adapted to be connected toa source of liquid to be pumped, and a check valve for preventingreverse flow of liquid through said pump, a chamber having a branch ductconnected to said inlet duct, a constantly-operating vacuum pumpconnected to said chamber to tend to maintain sub-atmospheric pressuretherein to reduce pressure in said inlet duct and to effect a flow ofliquid into said chamber, a float in said chamber, an atmospheric valveconnected to said float to be opened upon upward movement of the floatand closed upon downward movement thereof to maintain in said chamberthe proper sub-atmospheric pressure necessary to maintain liquid in sa dchamber at a prede termined level above said inlet duct, and valve meansfor closing said branch duct upon an increase in pressure in saidchamber approximately to atmospheric pressure.

8. In a liquid pumping system comprising a centrifugal pump having anoutlet duct and an inlet duct adapted to be connected to a source ofliquid to be pumped, and a check valve for preventing reverse flow ofliquid through said pump, a chamber having a branch duct connected tosaid inlet duct, a constantly-operating vacuum pum connected to saidchamber to tend to maintain sub-atmospheric pressure therein to reducepressure in said inlet duct and to effect a flow of liquid into saidchamber, a float in said chamber, an atmospheric valve connected to saidfloat to be opened upon upward movement of the float and closed upondownward movement thereof to maintain in said chamber the propersub-atmospheric pressure necessary to maintain liquid in said chamber ata predetermined level above said inlet duct, a valve in said branch ductbiased to closed position, a fluid pressure responsive element connectedto said valve, a casing forming with said pressure responsive element achamber communicating with said first named chamber, the other side ofsaid pressure responsive element being subject to atmospheric pressureto tend to maintain said valve in open position.

9. In a liquid pumping system comprising a centrifugal pump having anoutlet duct and an inlet duct adapted to be connected to a source ofliquid to be pumped, and a check valve for preventing reverse flow ofliquid through said pump, a chamber having a branch duct connected tosaid inlet duct, a constantly-operating vacuum pump connected to saidchamber to tend to maintain sub-atmospheric pressure therein to reducepressure in said inlet duct and to effect a flow of liquid into saidchamber, a float in said chamber, an atmospheric valve connected to saidfloat to be opened upon upward movement of the float and closed upondownward movement thereof to maintain in said chamber the propersub-atmospheric pressure necessary to maintain liquid in said chamber ata predetermined level above said inlet duct, valve means for closingsaid branch duct upon an increase in pressure in said chamberapproximately to atmospheric pressure, a condensation chamber, saidvacuum pump having an outlet connected to said condensation chamber, andfloat controled means for connecting said condensation chamber to saidfirst named chamber upon the accumulation of condensate in saidcondensation chamber above a predetermined level.

CORNELIUS KROLL.

REFERENCES CITED The following references are of record in the file ofthis patent:

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